Bovine serum albumin (BSA) is used as a diluent or a blocking agent in numerous applications including ELISAs (Enzyme-Linked Immunosorbent Assay), blots and immunohistochemistry. Additionally, native BSA is routinely used to enhance the stability of proteins during or after their purification, or in biological assays and to prevent adhesion of the enzyme to reaction tubes and other vessels.
In recent years, there has been a mounting concern over the use of animal products in many pharmaceutical and biotech industry applications because of the threat of animal viruses and transmissible sponge-form ensephelopathies (TSEs; the causative agent of mad cow disease) that may be present in bovine-derived BSA. Current methods of preparation of BSA involve purification of the protein from bovine plasma and testing for the presence of these contaminating agents. However, testing can only detect known viruses or TSEs and does not uncover infectious agents that have not yet been discovered. Therefore, there is currently no alternative large-scale supply of BSA that is assured to be free of all animal-derived infectious agents. Additionally, until this work, it was unclear whether a recombinant BSA (rBSA) would possess the same protein stabilizing characteristics as its native counterpart.